氮铂混合改性石墨烯吸附汞污染物的研究

DFT study on Adsorption Behavior of Mercury Pollutants towards Nitrogen-Platinum Modified Graphenes

为了研究氮铂混合改性石墨烯对燃煤电厂产生汞污染物的吸附作用,基于量子化学理论构建了氮铂混合改性石墨烯模型,利用密度泛函理论模拟了烟气中汞污染物在氮铂混合改性石墨烯表面的吸附。计算得到了Hg^0、HgCl2和HgBr2在氮铂混合改性石墨烯表面的吸附构型和吸附能,并利用分子中的原子理论(Atoms in Molecule)和约化密度梯度(Reduced Density Gradient)方法研究了吸附体系的成键类型。结果表明:随着掺杂氮原子数目的增多,氮铂混合改性石墨烯吸附Hg^0、HgCl2和HgBr2能力得到提升。当掺杂3个氮原子时,氮铂混合改性石墨烯吸附单质汞吸附能为98.62 kJ/mol,其吸附能相比传统的碳基吸附剂有明显提升;此时Hg^0、HgCl2和HgBr2被吸附稳定后的产物中,汞原子和铂原子之间的作用力更加稳定。

Mercury pollutants are of global concern due to their high volatility and bioaccumulation,which are emitted by coal-fired power plants.In this paper,the mercury adsorption of nitrogen-platinum mixed modified graphenes was studied by establishing the model based on the theory of quantum chemistry.The adsorption configuration and adsorption energy of Hg0,HgCl2 and HgBr2 adsorbed on nitrogen-platinum-modified graphene were calculated by the density functional theory.The bonding types were analyzed by AIM(Atoms in molecule)theory and RDG(reduced density gradient)methods.As the number of doped nitrogen atoms increased,the ability of nitrogen-platinum mixed modified graphene to adsorb Hg0,HgCl2 and HgBr2 was improved.While three nitrogen atoms were doped,the adsorption energy of elemental mercury adsorbed on nitrogen-platinum mixed modified graphene was 98.62 kJ/mol,and its adsorption energy was significantly improved compared with traditional carbon based sorbent.At the same time,the interaction between Hg and Pt was more stable.